Method of room temperature covalent bonding

• US 20040235266A1
• Filed: 05/19/2003
• Published: 11/25/2004
• Est. Priority Date: 05/19/2003
• Status: Active Grant

• Current Assignee: Invensas Bonding Technologies, Inc. (Adeia Inc.)
• Original Assignee: Ziptronix Incorporated (Adeia Inc.)
• Inventors: Tong, Qin-Yi
• Granted Patent: US 7,109,092 B2
• Time in Patent Office: Days
• US Class Current: 438/455
• CPC Class Codes: B32B 2250/04 4 layers
• CPC Class Codes: B32B 7/04 Interconnection of layers
• CPC Class Codes: B81C 1/00357 involving bonding one or several substrates on a non-temporary support, e.g. another substrate
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/019 characterised by the material or arrangement of seals between parts
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/08059 comprising protrusions or indentations
• CPC Class Codes: H01L 2224/29186 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/80895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• CPC Class Codes: H01L 2224/80896 between electrically insulating surfaces, e.g. oxide or nitride layers
• CPC Class Codes: H01L 2224/80986 Specific sequence of steps, e.g. repetition of manufacturing steps, time sequence
• CPC Class Codes: H01L 2224/81894 Direct bonding, i.e. joining surfaces by means of intermolecular attracting interactions at their interfaces, e.g. covalent bonds, van der Waals forces
• CPC Class Codes: H01L 2224/81895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• CPC Class Codes: H01L 2224/8319 Arrangement of the layer connectors prior to mounting
• CPC Class Codes: H01L 2224/8385 using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 2224/83894 Direct bonding, i.e. joining surfaces by means of intermolecular attracting interactions at their interfaces, e.g. covalent bonds, van der Waals forces
• CPC Class Codes: H01L 2224/83896 between electrically insulating surfaces, e.g. oxide or nitride layers
• CPC Class Codes: H01L 2224/9202 : Forming additional connectors after the connecting process
• CPC Class Codes: H01L 2224/9212 : Sequential connecting processes
• CPC Class Codes: H01L 2224/92125 : the second connecting process involving a layer connector
• CPC Class Codes: H01L 24/26 : Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/29 : of an individual layer connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/92 : Specific sequence of method steps
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01016 : Sulfur [S]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01058 : Cerium [Ce]
• CPC Class Codes: H01L 2924/01067 : Holmium [Ho]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/05442 : SiO2
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 2924/3512 : Cracking
• CPC Class Codes: Y10T 156/10 : Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/24355 : Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/31504 : Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A method of bonding includes using a bonding layer having a fluorinated oxide. Fluorine may be introduced into the bonding layer by exposure to a fluorine-containing solution, vapor or gas or by implantation. The bonding layer may also be formed using a method where fluorine is introduced into the layer during its formation. The surface of the bonding layer is terminated with a desired species, preferably an NH₂ species. This may be accomplished by exposing the bonding layer to an NH₄OH solution. High bonding strength is obtained at room temperature. The method may also include bonding two bonding layers together and creating a fluorine distribution having a peak in the vicinity of the interface between the bonding layers. One of the bonding layers may include two oxide layers formed on each other. The fluorine concentration may also have a second peak at the interface between the two oxide layers.

Claims

1. A bonding method, comprising:

forming first and second bonding layers on respective first and second elements, at least one of said bonding layers comprising a fluorinated oxide layer;

bringing into contact said first and second bonding layers in ambient at room temperature; and

forming a bond between said first and second layers at room temperature.

2. A method as recited in claim 1, comprising:

forming a bond of at least 600 mJ/m² at room temperature.

3. A method as recited in claim 1, comprising:

forming a bond of at least 1000 mJ/m² at room temperature.

4. A method as recited in claim 1, comprising:

forming a bond of at least 2500 mJ/m² at room temperature.

5. A method as recited in claim 1, comprising:

forming each of said first and second bonding layers to have a surface roughness in a range of about 0.1 to 1.5 nm.

6. A method as recited in claim 5, comprising:

activating said first and second bonding layers.

7. A method as recited in claim 1, comprising:

activating said first and second bonding layers.

8. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

exposing said layer to a fluorine-containing solution.

9. A method as recited in claim 8, comprising:

baking said at least one of said layers comprising a fluorinated oxide.

10. A method as recited in claim 9, comprising:

exposing said at least one of said layers to an RCA solution after said baking.

11. A method as recited in claim 9, comprising:

baking said at least one of said layers comprising a fluorinated oxide at a temperature of in a range of about 100-300°

C.

12. A method as recited in claim 9, comprising:

baking said at least one of said layers comprising a fluorinated oxide at a temperature of about 250°

C.

13. A method as recited in claim 9, comprising:

exposing said at least one of said layers to an RCA solution after said baking.

14. A method as recited in claim 8, comprising:

exposing said layer to a solution containing HF.

15. A method as recited in claim 8, comprising:

exposing said layer to a solution containing about 0.025% HF.

16. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

exposing said oxide layer to a fluorine-containing gas.

17. A method as recited in claim 16, comprising:

exposing said oxide layer to HF vapor.

18. A method as recited in claim 16, comprising:

exposing said oxide layer to a plasma containing one of SF₆ and CF₄.

19. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises depositing an oxide using a gas containing F.

20. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises depositing a PECVD oxide using a gas containing one of SiF₄, CF₄ and Si₂H₆.

21. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

implanting a F-containing species into said oxide layer.

22. A method as recited in claim 21, comprising:

implanting a F-containing species into said oxide layer to a dose in a range of about 1×

10¹⁵ to 1×

10¹⁶/cm².

23. A method as recited in claim 1, comprising:

etching said first and second bonding layers by exposure to an RIE process.

24. A method as recited in claim 1, comprising:

exposing said bonding layers to one of an NH₄OH solution and vapor.

25. A method as recited in claim 1, comprising:

covering first portions said first bonding layer; and

fluorinating second portions of said first bonding layer not covered in said covering step; and

bonding said second portions to said second bonding layer.

26. A method as recited in claim 1, wherein forming said fluorinated oxide in one of said first and second bonding layers comprises:

exposing a first oxide layer to fluorine; and

forming a second oxide layer on said first oxide layer after said exposing step.

27. A method as recited in claim 26, comprising:

forming said second oxide layer at a temperature in a range of about 100-300°

C.

28. A method as recited in claim 26, comprising:

forming said second oxide layer at a temperature of about 250°

C.

29. A method as recited in claim 1, comprising:

forming at least one of said first and second bonding layers to have a fluorine concentration of at least 10 ¹⁷/cm³.

30. A method of forming a bonded structure, comprising:

bonding first and second bonding layers; and

forming a fluorine concentration having a first peak in the vicinity of an interface between said first and second bonding layers and a second peak in at least one of said first and second layers separated from said first peak and located a distance from said first peak.

31. A method as recited in claim 30, wherein forming one of said first and second bonding layers comprises:

forming a first oxide layer;

introducing fluorine into said oxide layer; and

forming a second oxide layer on said first oxide layer after said introducing step.

32. A method as recited in claim 31, comprising:

diffusing fluorine from said first oxide layer into said second oxide layer.

33. A method as recited in claim 31, comprising:

exposing said first oxide layer to one of a solution, vapor and gas each containing fluorine.

34. A method as recited in claim 31, wherein:

forming said first oxide layer comprises depositing an oxide using a gas containing fluorine.

35. A method as recited in claim 31, comprising:

exposing said first oxide layer to a plasma containing one of SF₆ and CF₄.

36. A method as recited in claim 31, wherein forming said first oxide layer comprises depositing an oxide using a gas containing F.

37. A method as recited in claim 31, wherein forming said first oxide layer comprises depositing a PECVD oxide using a gas containing one of SiF₄, CF₄ and Si₂H₆.

38. A bonded structure, comprising:

first and second elements;

first and second bonding layers respectively formed on said first and second elements;

said first bonding layer non-adhesively bonded to said second bonding layer; and

said first bonding layer comprising a fluorinated oxide.

39. A structure as recited in claim 38, wherein:

said first bonding layer comprises a first oxide layer formed on a second oxide layer; and

a fluorine concentration in said first bonding layer has a first peak located in the vicinity of an interface between said first and second bonding layers and a second peak located at an interface between said first and second oxide layers.

40. A structure as recited in claim 38, wherein said first bonding layer comprises a fluorine-implanted layer.

41. A structure as recited in claim 38, wherein said first bonding layer comprises a layer having a surface etched with a fluorine solution.

42. A structure as recited in claim 38, wherein said first bonding layer comprises a oxide layer having a surface etched with a solution containing HF.

43. A structure as recited in claim 38, wherein said first bonding layer comprises a first oxide layer formed at a temperature in a range about 100-250°

C. on a second oxide layer containing fluorine.

44. A structure as recited in claim 38, wherein said first bonding layer comprises a first oxide layer formed at about 250°

C. on a second oxide layer containing fluorine.

45. A structure as recited in claim 38, wherein said first bonding layer comprises a oxide layer implanted with a F-containing species to a dose in a range of about 1×

10¹⁵ to 1×

10¹⁶/cm².

46. A structure as recited in claim 38, wherein said first bonding layer comprises a layer have a plurality of discrete regions containing fluorine.

47. A structure as recited in claim 38, wherein said first bonding layer comprises a surface terminated with at least one of S₁—

NH₂ and Si—

OH.

48. A structure as recited in claim 38, wherein said first bonding layer comprises a surface terminated with S₁—

NH₂ and Si—

OH.